The pulling force of a caterpillars calculated from the motor torque (Horsepower) all the way through the gearboxes, gears and chains to the belts. Then it has to be experimentally confirmed or measured by pulling trials at maximum belt clamping force. This is because of drive train horsepower loses and possible belt slippage.

Most engineers just size caterpillars from machine manufacturers catalogs or ask machine manufacturers to recommend and then quote their recommended caterpillar.